A tank of liquid helium, called the "cryostat", acts as a
coolant - producing a freezing vapor that cools the entire CTA to about five
degrees Kelvin (-459 Fahrenheit, or -268 Celsius).

To prevent the liquid helium from being used up too quickly,
the CTA is attached to the telescope with special insulating struts, and is
surrounded by a series of thermal radiation shields that prevent heat from the
spacecraft from reaching the telescope.

The outer shell of the Observatory is made of aluminum. It
is painted black on the side facing away from the Sun, to radiate as much heat
into space as possible, and is shiny on the Sun-facing side, to reflect the
Sun's light instead of absorbing it. The solar array and the spacecraft shields
block the CTA from the Sun and the rest of the spacecraft at all times, helping
to keep the CTA as cool as possible.

The Spitzer Space Telescope is a NASA mission managed by the Jet Propulsion Laboratory. This website is maintained by the Spitzer Science Center, located at IPAC on the campus of the California Institute of Technology.